Although the structure of ketones I' is rather similar to that of the ionones or to that of the ketone compounds described in particular in Helv. Chim. Acta, 53, 541, (1970), especially damascenone, ##SPC3##
we have surprisingly found that the odoriferous and flavouring characteristics of the compounds of the present invention are clearly different from those shown by the analogous compounds referred to. This fact illustrates once more the feature of surprise which is generally connected to the phenomena of olfactive and gustative perception. Indeed, we must stress the fact that in spite of the great number of theories hitherto developed in order to define the detection of the specific signaling obtained in the presence of a particular chemical compound, we must admit that at the present state of knowledge there is no theoretical relationship which would enable to predict with certainty the odour or the taste of a given chemical compound.
Whereas the ionones have a typical and intense odour of violets [see for example: P. Z. Bedoukian, Perfumery and Flavouring Synthetics, Elsevier Publ. Co. (1967) and Fortschritte der Chemie organischer Naturstoffe, VIII, 146 (1951)] and the unsaturated ketone compounds of the "damascenone" type [see: Helv. Chim. Acta, 53, 541 (1970)] are odoriferous constituents of distilled Bulgarian rose oil, we have now found that the diketone or keto-hydroxyl compounds of formula I' develop a mint-like, slightly musky odour which is sometimes reminiscent of aromatic herbs such as marjoram.
The novel compounds disclosed in the present application namely include the compounds of formula ##SPC4##
wherein: